This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-196205, filed Jul. 9, 1999; No. 11-196208, filed Jul. 9, 1999; and No. 11-203052, filed Jul. 16, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a method of selectively forming a copper film used as an interconnect material in an LSI or a liquid crystal display.
Aluminum (Al) is mainly used as an interconnect material in an LSI or a liquid crystal display. However, since Al has a higher resistance than that of copper (Cu), an Al interconnection delays signals and increases consumption power by heat generation. Therefore, Cu is attracting attention as an interconnect material of the next generation.
A Cu interconnection has been realized only by dry etching in a high-temperature atmosphere and hence is impractical at present. Although Cu can also be processed by wet etching, no microfabrication is possible.
As described above, a Cu interconnection is difficult to form by etching, so in the fabrication of an LSI the formation of Cu interconnection by CMP (Chemical Mechanical Polishing) is partially put into practical use.
Unfortunately, when CMP is applied to the formation of interconnecting lines in a liquid crystal display, it is practically difficult to form Cu interconnectins by CMP because the substrate of a liquid crystal display has a large area. Also, even when etching or CMP of Cu is possible in a liquid crystal display, the total area of Cu interconnections is smaller than the area of a glass substrate, so most of Cu films formed on this glass substrate are removed when Cu interconnections are formed. This significantly lowers the use efficiency of Cu that is an expensive material. That is, most of Cu films formed are wasted, and the price of a liquid crystal display increases.
It is an object of the present invention to provide a copper film selective formation method capable of reducing the material cost by selectively depositing copper in a necessary region of an undercoat film made of an arbitrary material such as a metal or an insulating material.
According to the present invention, there is provided a copper film selective formation method comprising the steps of:
forming a thin film made of a hydrophobic material on an undercoat film on a substrate;
making a prospective copper film region of the thin film hydrophilic; and
selectively forming a copper film in the hydrophilic prospective copper film region of the undercoat film by CVD of copper.
Also, according to the present invention, there is provided a copper film selective formation method comprising the steps of:
forming a thin film having a hydrophobic surface on an undercoat film on a substrate;
selectively forming an opening in a prospective copper film region of the thin film;
depositing a copper film primarily on the undercoat film exposed in the opening of the thin film by CVD of copper; and
removing the thin film.
Furthermore, according to the present invention, there is provided a copper film selective formation method comprising the steps of:
forming an undercoat film on a substrate;
forming a conductor pattern on the surface of the undercoat film, the conductor pattern being made of a material other than copper and having higher conductivity than that of the undercoat film; and
selectively depositing a copper film on the conductor pattern by CVD of copper.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.